Barnes slave-boson approach to the two-site single-impurity Anderson model with non-local interaction

¹  Laboratoire CRISMAT UMR CNRS-ENSICAEN 6508 - 6 Bld. Maréchal Juin, 14050 Caen Cedex, France, EU
²  LASMEA, UMR CNRS-Université Blaise Pascal 6602 - 24 avenue des Landais, 63177 Aubière Cedex, France, EU
³  Center for Electronic Correlations and Magnetism, EP VI, Universität Augsburg - D-86135 Augsburg, Germany, EU

Corresponding author: Raymond.Fresard@ensicaen.fr

Received: 29 January 2008
Accepted: 14 March 2008

Abstract

The Barnes slave-boson approach to the single-impurity Anderson model extended by a non-local Coulomb interaction is revisited. We demonstrate first that the radial gauge representation facilitates the treatment of such a non-local interaction by performing the exact evaluation of the path integrals representing the partition function, the impurity hole density and the impurity hole density autocorrelation function for a two-site cluster. The free energy is also obtained on the same footing. Next, the exact results are compared to their approximations at saddle-point level, and it is shown that the saddle point evaluation recovers the exact answer in the limit of strong non-local Coulomb interaction, while the agreement between both schemes remains satisfactory in a large parameter range.